Soldered aluminum-to-copper connection



July 4, 1950 J. ROGOFF SOLDERED ALUMINUM-TO-COPPER CONNECTION Filed May 18, 1945 17 TIN COAT 16 COPPER PLATE 15 z/Nc F145 10 AL {/Ml/VUM I IIIIII!!!IIIIIIIIII/IllI/Il IIIIIIIII Rw v 2 im mfm Patented July 4, 1950 SOLDERED ALUMINUM-TO-COPPER CONNECTION Julian Rogofl', New Rochelle, N. Y., assignor to Burndy Engineering Company, Inc., a, corporation of New York Application May 18, 1945, Serial No. 594,406 2 Claims. (c1.173324) My invention relates to electrical connections between aluminum and copper, or coppor alloy parts.

One object of my invention is to provide an aluminum connector or conductor which can be soldered to a connecting device.

Another object of my invention is to eliminate the electrochemical corrosion which occurs when aluminum and copper are in contact in presence of an electrolyte such as moisture, etc.

Still another object of my invention is to provide an aluminum conductor which can be joined or connected by conventional soldering, clamping or indenting means without the usual special precautions to remove or break down the oxide film on the surface of the aluminum.

I accomplish these and other objects and obtain my new results as will be apparent from the device described in the following specification, particularly pointed out in the claims, and illustrated in the accompanying drawing in which:

Fig. 1 is a side view of an aluminum connector partially in section, and coated to enable it to be soldered.

Fig. 2 is a cross-section of a piece of aluminum conductor.

Fig. 3 is a side view, partially in section, showing my aluminum connectors soldered to the pins or sockets of a plug and receptacle connector.

In Fig. 1 of the drawing I have illustrated in section an aluminum connector ii. In Fig. 2,

I have shown in section an aluminum cable l8.

In order to solder the aluminum, I have provided essentially three coatings therefor, which will be described more in detail hereafter.

The aluminum connector l0, comprises a tubular body section II, having a bore 12, and an extending pin member 13.

A typical use for such an aluminum connector is illustrated in Fig. 3, wherein the connector I0 is shown inserted into a tubular sleeve 22 which may have a semi-cylindrical portion of it removed at its tip to facilitate soldering the pin l3, as at 23. The sleeves 22, two of which are shown, are secured to the plug and receptacle body 24, illustrated as of the AN type, and the pin to sleeve connector may be encased in an insulating sleeve 25 If the aluminum cable I8 is coated as indicated in Fig. 2, the cable may be directly inserted into the sleeve 22, and soldered thereto. If the aluminum cable is not so coated, the connection to the connector l0 may be made by indenting, as at 26, wherein the treatment described in copending application No. 591,813, filed May 3, 1945,

2 which has issued into Patent No. 2,423,290 on July 1, 1947, may be employed.

The coatings for the aluminum connector ID are identified as the zinc flashing IS, the copper plating I6, and the final coating of tin I 1. These, in the case of the aluminum cable 18, are referred to as I9, 29, and 2| respectively.

Specifically I have provided the coatings by employing the following procedure and materials:

(l) Degrease the aluminum in a vapor or emulsion cleaner, carbon tetrachloride being an example. Avoid alkalis.

Rinse in hot water.

Etch for 3'minutes at 185 to 200 F. in tri-sodium phosphate.

Rinse in cold water.

Dip in nitric acid for 15 seconds at room temperature.

Rinse in cold water.

dry thoroughly.

The tin employed should be approximately tin and 35% lead. The above fundamentally employs the three basic steps, namely zinc-flashing which simultaneously removes the aluminum oxide from the aluminum and replaces it with a coating of zinc; copper plating; and finally placing the tin or final coat which permits soldering the coated aluminum to a copper or copper alloy part.

By the foregoing type of coating I have eliminated any possibility of electrochemical corrosion, and I can join an aluminum part to a copper part by conventional soldering, clamping or indenting means, which objectiv I have sought to attain. I

In place of zinc flashing I may use other metals such as cadmium which will replace the aluminum oxide by a more permanent coating. Additional other metals may be used in place of copper plating; i. e. silver plating may be employed. The final solder coating too may be of any soldering material which will readily adhere to the electro plated coating and permit soldering thereto.

I have thus described my invention, but I de- Zinc flash. Immersion dip in a solution of; zinc salts for 1 minute at room temperature.

sire it understood that it is not confined to the particular forms or uses shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of my invention, and, therefore, I claim broadly the right to employ all equivalent instrumentalities coming within the scope of the appended claims, and by means of which, objects of'my invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to attain these objects and accomplish these results.

I claim:

1. A soldered electrical connection for aluminum-to-copper conductors comprising analuminum conductor, an aluminum connector having a body portion provided with a socket containing the conductor end, said body portion being indented into the aluminum conductor, said connector terminating in an extending portion sol- .dered to a copper conductor, 'said extending portion having an aluminum-oxide free surface zincflashed, copper plated, and tin coated, which tin coating is soldered to the copper conductor to form a soldered aluminum-to-copper connection of high electrical joint efilciency.

2. A solderable aluminum connector for transmitting current from an aluminum conductor to a copper surface, comprising a connector body having a socket for receiving the conductor, said connector body having a wall thickness capable of being indented to the conductor, said conductor terminating in an extending portion having a 4 substantially aluminum oxide-free surface formed integrally with the connector body, said aluminum oxide-tree surface of the extending portion covered with a zinc flash, an outer solderable coating of tin and an intermediate copper plate coating to obtain maximum electrical current carrying efllciency between the aluminum conductor and the copper surface.

JULIAN ROGOFF.

RE ERENCES CITED The following references are of record in the tile or this patent:

UNITED STATES PATENTS Number Name Date 536,152 Legate Mar. 19, 1895 1,147,718 Hall July 27, 1915 1,875,241 Idank Aug. 30, 1932 2,068,639 Alsaker Jan. 26, 1937 2,309,563 Abeel Jan. 26, 1943 2,405,111 Carlson Aug. 6, 1946 FOREIGN PATENTS Number Country Date 3,668 Great Britain Feb. 14, 1898 5,055 Great Britain Oct. 15, 1908 15,105 Great Britain Oct. 7, 1909 130,586 Great Britain June 19, 1919 minum Co. of America, copyright 1930, page 32.

"The Metal Industry," May 29, 1931, page 556. 

